Furnace Controls Using High Temperature Preheated Combustion Air

Abstract

GTE Products Corporation (Towanda) has developed a compact cross flow recuperator for high temperature industrial heat recovery applications. During the development of the ceramic recuperator, GTE interfaced with major combustion equipment manufacturers to ascertain the optimum types of combustion control that can be used with preheated air. Preheated air and its effect (increased pressure from expanded gases) on static pressure complicate the control process. Standard practices that dictate precision stoichiometric control over wide ranges of thermal inputs will be outlined. System performance with ambient air and preheated air will be discussed as will the effect of stoichiometry for each system.

Mechanically linked, flow balanced, cross connected and electronic ratio controllers are to be explained. A method to perform a cost performance analysis for each system will be detailed. Basic combustion control principles and the effect of preheated air on optimization and control will be shown. Sophisticated controls are only necessary because of process load demands, and preheated air (from recuperators) allows for greater tolerances of ratio variations over controlled turndown spans.